President Barack Obama's choice for deputy secretary of the Homeland Security Department testified today about his plans for the agency, even as he remains a target of an internal watchdog's investigation into his leadership of U.S. Citizenship and Immigration Services.

Alejandro Mayorkas told members of the Senate Committee on Homeland Security and Governmental Affairs Thursday that allegations that he used his position to influence a decision regarding a company run by the brother of former Secretary of State Hillary Rodham Clinton are false, and that he did not even know about the investigation until reports were released Monday night.

"It was Monday evening when I was forwarded a copy of the email that was published to this committee about an apparent inspector general investigation of which I, reportedly, am a subject," Mayorkas said in the hearing. "I had no idea of the existence of that investigation and, quite frankly, I still don't understand it. I will say this, and I say it firmly and I say it unequivocally, and I say it after 16 years of service to this country... I have never ever in my career exercised undue influence to influence the outcome of the case. I have never based my decisions on who brings a case, but rather upon the facts and the law."

Mayorkas, currently the director of U.S. Citizen and Immigration Services (USCIS), is under investigation by the DHS inspector general for allegations that he used undue influence to help secure an international investor visa for an executive in a company run by Anthony Rodham.

The company, Gulf Coast Funds Management LLC, sought the visa under CIS's EB-5 program. The program provides visas and the potential for citizenship for foreign investors who invest between $500,000 and $1 million in projects that create jobs for U.S. citizens.

No Republicans attend hearing

No Republican senators, including Ranking Member Sen. Tom Coburn (R-Okla.), attended the hearing to question Mayorkas. Coburn issued a statement this morning that said asking Mayorkas to testify in the light of the investigation is 'unfair and improper," as any sworn testimony could complicate any legal strategy Mayorkas may have in the future.

Coburn said holding a hearing during an active investigation appears to be unprecedented. It is unclear how the absence of Republican senators to question Mayorkas in the hearing will affect his confirmation.

Mayorkas did answer Democrats' questions about his plans for DHS if he is confirmed on issues of employee morale and the holes in DHS's leadership framework.

Moyorkas said he would work to provide DHS employees with the tools they need for success.

"It would be my responsibility, should I have the honor of being confirmed, to ensure that our workforce has the tools that they require to perform their work at the very highest levels of excellence to which they aspire, that they feel fully engaged in the execution of the mission, that they feel fully supported, that they are trained, that they are provided with transparent and open and fair processes," Mayorkas said.

Confirming Mayorkas would be one step in filling the numerous gaps in DHS leadership. Secretary Janet Napolitano resigned earlier this month, as did Deputy Secretary Jane Lute earlier this year. Committee Chairman Sen. Tom Carper (D-Del.) said that currently, 15 of the leadership positions at DHS are, or will soon be, vacant.